Prothonotary Warbler

Protonotaria citrea

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Figure 1. Distribution of the Prothonotary Warbler.

Adult male Prothonotary Warbler; Arkansas, April

Big Woods, Arkansas, 13 April 2005.; photographer Brian L. Sullivan

One of the most striking wood-warblers of North America, the Prothonotary Warbler intrigues and delights those who visit its swampy world. The only mem-ber of the genus Protonotaria, the species was named for its plumage, which resembles the bright yellow robes of papal clerks (prothonotaries) in the Roman Catholic church. This warbler also holds a place in recent U.S. history by being partly responsible for the conviction of alleged spy Alger Hiss and the corresponding political rise of Richard Nixon.

Although Hiss repeatedly denied ever knowing Whittaker Chambers, the ex- communist who accused him of espionage, Chambers had testified that the men were friends. To verify this, Chambers admitted knowledge about many personal issues, including that Hiss was an amateur ornithologist who had been excited at seeing a Prothonotary Warbler along the Potomac River. When asked later, Hiss independently admitted that he had seen the warbler along the river. As a member of the House Un-American Activities Committee investigating the Hiss allegations, freshman congressman Richard Nixon played a prominent role in proving that the two men knew each other and that Hiss had perjured himself.

A medium-distance migratory species, the Prothonotary Warbler inhabits wet forests throughout its range. In breeding areas, primarily in the southeastern United States, it is a bird of bottomland hardwood forests and other forested wetlands. It winters in mangrove (Avicennia spp.) forests of Central and South America. This warbler has the further distinction of being the only eastern wood-warbler that nests in tree cavities. It often uses holes excavated by Downy Woodpeckers (Dryobates pubescens), but the prothonotary also nests in a variety of other cavities.

Because the species has specific habitat needs in breeding and wintering areas, the greatest threats to its survival are degradation and destruction of its habitat. Logging and agricultural conversion of bottomland hardwood forests throughout the southeastern United States have been detrimental to breeding populations. An even greater threat may be the rapid destruction of mangrove habitats in northern South America, where the greatest numbers of prothonotaries overwinter.

Insights into the breeding ecology of this warbler were provided by the extensive studies of Walkinshaw (
Walkinshaw, L. H. (1938b). Nesting studies of the Prothonotary Warbler. Bird-Banding no. 9:32-46.
Walkinshaw 1938b,
Walkinshaw, L. H. (1939a). Additional information on the Prothonotary Warbler. Jack-Pine Warbler no. 17:64-71.
Walkinshaw 1939a,
Walkinshaw, L. H. (1941). The Prothonotary Warbler, a comparison of nesting conditions in Tennessee and Michigan. Wilson Bull. no. 53:3-21.
Walkinshaw 1941,
Walkinshaw, L. H. (1953a). Life-history of the Prothonotary Warbler. Wilson Bull. no. 65:152-168.
Walkinshaw 1953a) in Michigan and Tennessee. Additional work in Tennessee by LJP and colleagues in the mid-1980s examined aspects of territoriality, habitat selection, and mating system. Long-term research by Charles Blem in Virginia continues to address aspects of clutch-size variation, longevity, and nest-site selection. Because of its tame nature and ready acceptance of artificial nest sites, the Prothonotary Warbler has become a relatively popular study species, and may be a useful indicator species for environmental quality of forested wetlands. Nest box programs (e.g.,
Cartwright, L. (1997). Prothonotary Warbler nest box program in northern Virginia. Sialia no. 19:43-48.
Cartwright 1997) are proliferating across the breeding range to bolster diminished local populations, as park managers recognize the educational and aesthetic value of this colorful warbler to the general public.

Although the species has been studied fairly well in breeding areas, information about effects of habitat loss on migrating and wintering populations is currently lacking and is critical for future conservation and management of the species.